Communications networks, e.g. the Internet, are finding increasing use for commercial delivery of proprietary media/multimedia data to clients/users. Such data is in digital form, and may represent a still image, a video sequence, or an audio sequence of voice or music, for example. Rendering of time-based digital media such as audio, speech or video involves producing a series of outputs over a period of time, e.g., a video frame every 1/30-th of a second in the case of video NTSC output.
Where such data is proprietary, as under copyright, there are concerns with unauthorized access at intermediate points along the transmission path, as well as with users who have gained authorized access to the data then allowing others to copy and use the data without authorization. In view of such concerns, security measures are required for preventing contents from becoming available at intermediate points and for restricting access to the data to those who have been properly authorized. Such measures may include encryption as well as partitioning of data for transmission of the individual parts over distinct paths. In the latter case, parts are chosen so that no one of them provides a good approximation to the original content, thus requiring complete assembly of all parts for content to become available at good quality to an authorized recipient. Similar concerns arise with respect to security and privacy in communications over an open network, especially in real-time communication between users and in real-time broadcasting of potentially sensitive information.
Data representing media content tends to be voluminous, and its protection typically entails considerable complexity and transmission costs: in encryption, in transmission over a secure server, and in the use of streaming in preference to downloading to make copying more difficult.